Struct NonblockingInStream 

pub struct NonblockingInStream(/* private fields */);

An adapter to make an InStream non-blocking from the sender’s perspective

By default, OutStreams are blocking: receiving client(s) have finite buffering, and once it is full they must drain the buffer before another message can be sent. This can produce undesirable behavior, especially with broadcast streams where some clients are slow to read.

This adapter can be used to prevent the slow receiver problem. Specifically, any client that wraps an InStream with this adapter will automatically read messages into a ring buffer upon arrival. If the ring buffer becomes full, the oldest message will be overwritten. At the next read, the client will get a NonblockingInStreamError::Lagged error indicating that they have missed some number of messages, after which they can resume reading messages from the stream as normal.

Note that to prevent blocking for broadcast streams, all clients must apply this adapter to their InStream. This library does not enforce this—it is up to the application to do so. It is possible to mix nonblocking and blocking clients, e.g., making only the slow clients nonblocking.

This adapter is compatible with tokio-serde’s Framed struct, and in particular it should work with any of the tokio_serde::formats codecs. See tests.rs and the crate-level documentation for examples.

Implementations

impl NonblockingInStream

pub fn new(recv: InStream, buflen: usize) -> Self

Create a new NonblockingInStream from a broadcast InStream with a buffer of size buflen

This constructor should only be used for broadcast streams. See also NonblockingInStream::new_unicast.

pub fn new_unicast(recv: InStream, buflen: usize) -> Self

Create a new NonblockingInStream from a unicast InStream with a buffer of size buflen

This constructor should only be used for unicast streams. See also NonblockingInStream::new.

Trait Implementations

impl FusedStream for NonblockingInStream

fn is_terminated(&self) -> bool

Returns true if the stream should no longer be polled.

impl Stream for NonblockingInStream

type Item = Result<BytesMut, NonblockingInStreamError>

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.